There exists a plethora of variables that affect performance of a turbine engine. One such variable that has been identified in dry-low NOx combustor design turbines is the air flow distribution between the combustor zone and the leakage air flows. Typically, a spring clip seal is used in such a turbine engine to direct gases, such as common air, into a combustor basket where the air mixes with fuel. Conventional spring clip seals direct air through center apertures in the seals and are formed from outer and inner housings. The seals are generally cylindrical cones that taper from a first diameter to a second, smaller diameter. The first diameter is often placed in contact with a transition inlet ring, and the second, smaller diameter is often fixedly attached to a combustor basket. The inner and outer housings include a plurality of slots around the perimeter of the housings which form leaves in the housing. The leaves are capable of flexing and thereby imparting spring properties to the spring clip seal. This spring force assists in at least partially sealing the inner housing to the outer housing.
Conventional spring clips allow up to 8% of the total air flow distribution flowing through a center aperture of a spring clip seal to leak through the seal. Such leakage can often cause undesirable outcomes. For instance, air leakage at this level can cause high engine performance variability, which is characterized by high NOx emissions, high dynamics or flashback, or any combination thereof.
Turbine spring clip seals have attempted to reduce leakage across the seal by configuring the inner housing and the outer housings to correspond to each other, thereby reducing leakage across the seal. However, each hundredth of an inch that separates the inner housing from the outer housing results in air leakage of about 2% of the total air flow through the center aperture of the spring clip seal. Thus, for a separation of about 3/100s of an inch between the inner and outer housings, which is common, the spring clip seal yields leakage of about 6% of the total air flow through the center aperture in the seal.
Therefore, there is a need for an improved turbine spring clip seal that reduces the amount of air leaking between an inner housing and an outer housing of the seal.